As disclosed in JP2002-362201A and JP2007-143835A, for example, a child car seat that is fixed on a seat of a vehicle by means of a vehicle seatbelt is generally known as a child car seat having a child belt for fixing a child. The child belt includes a crotch belt passing through between thighs of a child, and shoulder belts extending on shoulders. A plurality of through-holes through which the shoulder belt can pass are formed in a back part of the child car seat at different positions in a height direction. By suitably selecting a through-hole through which the shoulder belt passes, a support position of the child belt can be adjusted correspondingly to a growth step of a child.
However, in the child car seats of JP2002-362201A and JP2007-143835A, when one intends to pass the shoulder belt through another through-hole, he/she should carry out a complicated operation such as removal of an end portion of the child belt from a metal piece or a buckle. Namely, in the child car seats of JP2002-62201A and JP2007-143835A, it is not easy to adjust a position of the child belt.